Accessing objects of a window via another

After you open a secondary window, there is a connection between the
original window and this newly opened one that allows you to cross-access
objects/variables, properties of each window. But before we discuss how this
is done, we need to first discuss window names, a very different kind from
the target name mentioned in the previous page. Look at below:

var hello=open('page2.htm','hi','width=200,height=200')

By assigning this window to a variable upon opening it, we create a
connection to this window from the window that opened it. Whenever we want to access anything that's inside this newly
opened window, for example, to write to this window, we would do this:
hello.document.write("hi!") inside the
current window.

Ok, lets say you want to, from the current window, open a secondary
window, and FROM HERE, change the background color of this newly opened
window.

Then, click the below buttons:

Change background color:

...lightgreen:...lightyellow:...pink:

The radio buttons are here, but we have changed the bgcolor of another
window...lets see the core code:

The most important part is:
win1.document.bgColor, which is what caused the bgcolor to change in
the secondary window, instead of the one that contains the script. Also
notice that we used another method, focus(), to bring focus to the second
window every time it changes.